JP2006282914A - Method of manufacturing biomass coke - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing biomass coke usable in a domestic waste direct melting furnace or the like while reducing crushing power and molding power necessary to manufacture coke from biomass. <P>SOLUTION: The method includes a thermal decomposition process for separating the biomass into a thermal decomposition gas and solid carbonized matter at a temperature of 400-900°C by indirectly heating the biomass in an air-cut state; a gas reforming process converting a high boiling point liquid gas, which is contained in the thermal decomposition gas obtained by the thermal decomposition process and liquefied at normal temperatures and normal pressure, into low-boiling point gases, which are not liquefied at normal temperatures and normal pressure, such as hydrogen, carbon monoxide, and methane by a reforming reaction using a catalyst reacting at temperatures of 400-900°C; a gas purifying process for removing moisture, corrosive components and heavy metals in the gas by cooling and cleaning the reformed gas after reforming; and a pulverizing process for pulverizing solid carbonized matter obtained in the thermal decomposition process; and by a granulation process for adding a binder to the pulverized solid carbonized matter, pressurizing, molding and granulating them to manufacture the biomass coke. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing coke from unused biomass.

In recent years, in order to reduce CO ₂ from the viewpoint of preventing global warming, development related to the utilization of biomass resources capable of CO ₂ circulation and fixation in a short-term cycle has been promoted. A waste processing method and a waste processing apparatus are disclosed. This is a high-boiling liquid gas that separates waste containing biomass into pyrolysis gas and carbonization residue (carbide) in an indirect heating pyrolysis furnace, and then liquefies at normal temperature and normal pressure contained in the pyrolysis gas, The so-called tar is thermally decomposed by heat generated by partial combustion of the pyrolysis gas, and the obtained carbide is gasified in a melt gasification furnace.

  In the method of Patent Document 1, biomass carbide is gasified in a melt gasifier. However, when this biomass carbide is used as a coke for molten fuel in a general waste direct melting furnace, there are the following problems. It was.

1. When producing coke of a predetermined shape from biomass, it is necessary to pulverize biomass (non-distilled) and high-pressure molding. Especially when fiber biomass is used as raw material, a large amount of pulverization is required for pulverization and high-pressure molding. Power and molding power are required.

2. Conversely, when carbonizing a simply molded product for coking without performing pulverization and high pressure molding, sufficient strength of the molded carbide cannot be obtained and cannot be used as coke.

3. When carbonizing high-moisture biomass such as sewage sludge alone to produce coke, enormous external energy is required to dry the moisture.

4). When biomass is carbonized and coke, volatile components are gasified, and more gas is generated than the amount of heat necessary to carbonize and coke, but it cannot be effectively used because it contains tar. Is wasted. In the method of Patent Document 1, it is necessary to partially burn part of the pyrolysis gas generated in the pyrolysis furnace in order to pyrolyze the tar content in the pyrolysis gas, and to increase the temperature to 1000 ° C. or higher. The amount of heat generated from the gas is low, and the gas energy recovery rate is also low.
Japanese Patent Laid-Open No. 11-290810

  The problem to be solved by the present invention is to provide a method for producing biomass coke that can be used in a general waste direct melting furnace, etc., by reducing crushing power and molding power necessary for producing coke from biomass. It is in.

  Another problem is to eliminate troubles caused by tar contained in the pyrolysis gas obtained by pyrolysis of biomass so that the pyrolysis gas can be used effectively.

  Yet another challenge is to reduce or eliminate external energy for drying high moisture biomass.

  The method for producing biomass coke according to the present invention includes a pyrolysis step of separating biomass into a pyrolysis gas and a solid carbide of 400 to 900 ° C. by indirect heating in an air shut-off state, and in the pyrolysis gas obtained in the pyrolysis step. Converts high-boiling liquid gas liquefied at room temperature and normal pressure into low-boiling gases such as hydrogen, carbon monoxide, and methane that do not liquefy at room temperature and normal pressure by a reforming reaction using a catalyst that reacts at 400 to 900 ° C. Gas reforming process, gas reforming process for cooling and purifying the reformed gas after reforming to remove moisture, corrosive components and heavy metals in the gas, and solid carbide obtained in the pyrolysis process is pulverized A biomass coke is produced by a granulation step including adding a binder to the finely pulverized solid carbide and granulating by pressure molding.

  Thus, in the present invention, the solid carbide obtained by pyrolysis of biomass is finely pulverized, and the binder is added and pressure-molded, so that the binder sufficiently penetrates between the carbide particles, and the bonding strength is high. It is possible to produce high-strength biomass coke. And since the intensity | strength of the solid carbide | carbonized_material obtained by thermal decomposition of biomass is low compared with the original biomass, grinding | pulverization power and shaping | molding power can be reduced. Further, even when fibrous biomass is included as a raw material, it can be easily pulverized after carbonization and can be molded at high density. Furthermore, it is possible to mold a material having a low lignin content and difficult to be pressure-molded, such as a wood chip of construction waste, and it is possible to produce biomass coke regardless of the properties of the biomass raw material.

  In addition, by modifying the high-boiling liquid gas contained in the pyrolysis gas at room temperature and normal pressure, that is, the tar component with a catalyst, troubles due to the tar component can be eliminated. In addition, the reforming reaction can be promoted at a low temperature as compared to the case without a catalyst, and it is not necessary to partially burn the pyrolysis gas for gas reforming, so that the calorific value of the obtained gas can be kept high and at room temperature. The recovery rate of available gas energy is also increased.

  In the present invention, the refined gas obtained in the gas purification process is used as an external heat source for the thermal decomposition process, or the thermal decomposition process and the gas reforming process, and the power generation process for generating and using the surplus purified gas with a gas engine is provided. Can be included.

In the pyrolysis process, indirect heating is performed to provide the amount of heat for drying, heating, and pyrolysis of the biomass. In the gas reforming process, the endothermic reaction component of the tar decomposition is compensated and the catalyst is activated. Indirect heating is performed to maintain the temperature. By using the purified gas obtained in the gas purification process as the external heat source, it is not necessary to use external fuel or pyrolysis product gas, so that the energy recovery efficiency can be increased, and only biomass energy can be used. Therefore, the CO ₂ load on the environment can be reduced.

  As the pyrolysis furnace used in the pyrolysis step, an externally heated rotary kiln, an externally heated paddle, or a screw type transport reactor can be used for indirectly heating the biomass in an air shut-off state.

  The temperature range of the gas reforming step is 400 to 900 ° C, desirably 500 to 850 ° C, more desirably 550 to 800 ° C, and is determined by the temperature at which the catalyst is activated.

  In this gas reforming process, the temperature at the outlet of the pyrolysis process is increased, the endothermic reaction of the decomposition of tar is covered by the gas sensible heat, and the temperature at which the catalyst is activated is maintained at the outlet of the gas reforming process. In this case, heat compensation by indirect heating in the gas reforming step can be made unnecessary. That is, in the gas reforming step, by not performing indirect heating, the equipment can be configured simply and can be made inexpensive. At that time, the gas temperature at the outlet of the pyrolysis process is set as high as possible, and the catalyst used in the gas reforming process is one that reacts even at a lower temperature, for example, introduced into the gas reforming process at 900 ° C., and 500 ° C. However, if a reacting catalyst is used, the sensible heat of gas at 400 ° C. can be used for the endothermic reaction during the tar reforming.

  The catalyst used in the gas reforming process is a catalyst that promotes cracking (thermal decomposition) of the tar, or a catalyst that promotes the reaction of reforming the tar with water vapor. Silica-alumina, zeolite, dolomite, nickel-alumina Any of a nickel-based or nickel-magnesia-based catalyst, a cerium oxide support on which rhodium, rhodium, ruthenium, palladium or platinum is supported as a catalytic metal, or a mixed configuration thereof may be used. The temperature range at which the catalyst is activated varies depending on the material selected, but in any case, the reaction can be promoted by the catalyst, so that the tar content can be decomposed at a lower temperature than when there is no catalyst. The recovery rate of calories and gas is high.

  The catalyst reactor used in the gas reforming process is a fixed bed reactor filled with a vanicum or pellet catalyst, or a fluidized bed filled with a sand catalyst and fluidized by a gas flow. Any of the reactors can be used.

  The surplus purified gas remaining as an external heat source in the pyrolysis process and the gas reforming process is used for power generation in a power generation process using a gas engine. In this power generation process, since the purified gas obtained in the gas purification process is used, highly efficient power generation is possible.

  In addition, hydrogen can be separated from the obtained purified gas and used as fuel cell hydrogen, and the off-gas after hydrogen separation can be used as gas engine fuel.

  If the biomass to be used is low moisture biomass (moisture content: 50% by mass or less), it can be directly subjected to the pyrolysis step without going through the drying step. Examples of low moisture biomass include construction waste wood, woody biomass such as thinned wood, and paper.

  On the other hand, when using high moisture biomass (moisture content: more than 50 mass%), the dried biomass after drying this by a drying process is used for a thermal decomposition process. In this drying process, the external fuel for drying is dried by drying at least one of the external heat exhaust gas from the pyrolysis process and the gas reforming process and the exhaust gas from the power generation process. Can be made unnecessary. Examples of the high moisture biomass include sewage sludge, human waste sludge, their digested sludge, dehydrated sludge, livestock manure, food waste, or composted materials thereof or a mixture thereof.

  In this invention, the reheating process of reheating the obtained biomass coke (compression molding product of fixed carbide) to 800 degreeC or more can be included. By this reheating treatment, the hot strength of biomass coke can be further increased by bonding the carbon molecules with the carbon content in the binder to increase the degree of graphitization. Biomass coke obtained by the present invention can be used as coke for molten fuel in a general waste direct melting furnace such as a shaft furnace type melting furnace. In particular, the biomass coke reheated as described above is used. In this case, the combustion temperature increases because of the low volatile content.

  As described above, the present invention has the following effects.

1. Regardless of the nature of the biomass raw material, biomass coke that can be used in a general waste direct melting furnace or the like can be produced with less crushing power and molding power.

2. By modifying the tar content contained in the pyrolysis gas with a catalyst, troubles due to the tar content can be eliminated. Further, since the reforming reaction can be promoted at a low temperature as compared with the case without a catalyst, the recovery rate of gas energy that can be used at room temperature can be increased, and the power generation efficiency can be increased.

3. By using biomass-derived coke in a general waste direct melting furnace or the like, the amount of CO ₂ generated from fossil fuels can be reduced, contributing to global environmental conservation such as prevention of global warming.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a process diagram showing a method for producing biomass coke according to the present invention.

  In the figure, a high moisture biobath such as sewage sludge is subjected to a pyrolysis step after being dried in the drying step. An internal heating type drying furnace is used for the drying process, and as the heat source, an external heat exhaust gas in a thermal decomposition process and a gas reforming process, which will be described later, and an exhaust gas in a power generation process and a reheating process are used. By this drying step, the high moisture biobath is made dry biomass having a water content of about 5 to 20% by mass.

  On the other hand, low moisture biomass such as woody biomass is directly subjected to a pyrolysis process. An external heating type rotary kiln is used for the thermal decomposition process, the purified gas obtained in the gas purification process described later is introduced as a heat source for the external heating section, and burned at 700 to 1000 ° C. The external heat exhaust gas from the external heat section is used as a heat source for the drying process as described above.

  The kiln furnace shell of the externally heated rotary kiln is cut off from the external heating part, and the biomass charged in the kiln furnace shell is heated to 400 to 900 ° C. by indirect heating in an air shut-off state, dried, Pyrolysis and separation into pyrolysis gas and solid carbide.

Pyrolysis gas is a low boiling point gas mainly composed of CO, CO ₂ , H ₂ , and CH ₄ and a high boiling point liquid substance that is liquefied at room temperature. It consists of so-called tar and water vapor, and is 400 to 900 ° C. at the outlet temperature of the pyrolysis furnace process.

  This pyrolysis gas is introduced into a gas reforming process comprising a catalytic reactor, and the tar content in the pyrolysis gas is mainly composed of hydrogen, carbon monoxide, and methane by the reforming reaction using the catalyst in the catalytic reactor. Converted to low boiling point gas. The catalytic reactor is of the external heating type, and the purified gas obtained in the gas purification step described later is introduced as a heat source of the external heating portion and burned at a temperature of 700 to 1000 ° C. It indirectly compensates for the endothermic reaction heat. The external heat exhaust gas from the external heat part of the catalytic reactor is used as a heat source for the drying process as described above.

  The reformed pyrolysis gas (reformed gas) exiting the gas reforming process is cooled, dedusted, desulfurized, and desalted in a gas purification process using a scrubber. The temperature at the scrubber outlet is sufficiently lowered to 60 ° C. or less, more preferably 40 ° C. or less to suppress the contained water vapor, and a high-heat and clean pyrolysis gas (purified gas) is obtained. As described above, this purified gas is used as an external heat source in the thermal decomposition process and the gas reforming process. In this embodiment, a refining gas is used as a heat source for the reheating process described later. The surplus refined gas is used by the gas engine in the power generation process. As other uses of the purified gas, hydrogen can be separated from the purified gas and used as fuel cell hydrogen, and the off-gas after hydrogen separation can be used as a fuel for a gas engine in a power generation process.

  On the other hand, the solid carbide obtained in the pyrolysis step partially retains volatile matter depending on the pyrolysis temperature, but most of the solid carbide is a carbide composed of fixed carbon and ash, and has an outlet temperature of 400 to 400 at the pyrolysis step. 900 ° C.

  This solid carbide is finely pulverized, for example, to a particle size of 200 μm or less in the pulverization step. About 20% by mass of binder is added to the finely pulverized solid carbide as an outer shell, mixed, and pressure-molded in the granulation step to obtain biomass coke.

  As the binder, a tar / pitch binder, plastic, water, water glass, cement, cellulose, or a mixture thereof can be used, and a tar / pitch binder is preferably used. The pressure molding after mixing the binder is performed using a pressure molding machine such as an extrusion molding machine or a double roll molding machine, and the pressure is about 300 to 3000 MPa, for example.

  The biomass coke obtained in the granulation step is used as molten fuel coke in a general waste direct melting furnace such as a shaft furnace type melting furnace. Even if the temperature rises when using this melting furnace, the volatile matter is mainly the binder, so the strength during hotness can be maintained.

  In order to further increase the hot strength of the biomass coke, the biomass coke obtained in the granulation step is reheated to 800 ° C. or higher in the reheating step. As a result, carbon molecules are bonded to each other by the carbon content in the binder and the graphitization degree is increased, so that the hot strength of the biomass coke is further increased. An internal heating furnace is used for the reheating process, and the purified gas obtained in the purification process as described above is used as the heat source. Further, the exhaust gas from the reheating process is used as a heat source for the above-described drying process.

It is process drawing which shows the manufacturing method of the biomass coke of this invention.

Claims (8)

  A pyrolysis process in which biomass is separated into a pyrolysis gas of 400 to 900 ° C. and solid carbide by indirect heating in an air shut-off state, and a high temperature liquefaction at normal temperature and normal pressure contained in the pyrolysis gas obtained in the pyrolysis process A gas reforming step for converting a low-boiling point liquid gas into a low-boiling point gas such as hydrogen, carbon monoxide, and methane, which is not liquefied at room temperature and normal pressure, by a reforming reaction using a catalyst that reacts at 400 to 900 ° C. The refined gas was cooled and purified to remove moisture, corrosive components and heavy metals in the gas, and a pulverization step to finely pulverize the solid carbide obtained in the thermal decomposition step. A method for producing biomass coke, characterized in that biomass coke is produced by a granulation step in which a binder is added to solid carbide and granulated by pressure molding.   The power generation process includes using the purified gas obtained in the gas purification process as an external heat source for the thermal decomposition process, or the thermal decomposition process and the gas reforming process, and using the surplus purified gas for power generation by a gas engine. The manufacturing method of biomass coke as described.   The method for producing biomass coke according to claim 1 or 2, wherein the biomass to be subjected to the pyrolysis step is low moisture biomass such as construction waste wood and thinned wood.   It includes a drying process to dry high-moisture biomass by using at least one of the external heat exhaust gas from the pyrolysis process and gas reforming process and the exhaust gas from the power generation process, and the dry biomass obtained by this drying process is pyrolyzed The manufacturing method of the biomass coke of Claim 2 with which it uses for a process.   The biomass coke according to claim 4, wherein the high moisture biomass used is sewage sludge, human waste sludge, digested sludge thereof, dehydrated sludge, livestock manure, food waste, or composted materials thereof or a mixture thereof. Production method.   The manufacturing method of the biomass coke in any one of Claims 1-5 including the reheating process which reheats the obtained biomass coke to 800 degreeC or more.   The method for producing biomass coke according to any one of claims 1 to 6, wherein the obtained biomass is used as molten fuel coke in a shaft furnace type melting furnace for waste.   The method for producing biomass coke according to any one of claims 1 to 7, wherein hydrogen is separated from the obtained purified gas and used as fuel cell hydrogen, and off-gas after hydrogen separation is used as fuel for a gas engine.

Images